1. Field of the Invention
The present invention relates to an imaging device module which includes a lens and an image pickup device and which is used for taking digital images in an imaging device such as a digital camera or a camera integrated into a cellular phone, and more specifically, relates to an imaging device module which can be provided with functions such as a zooming function for varying the focal length of a lens system by moving one or more lens elements in an optical axis direction and an AF (autofocus) function for bringing an object into focus automatically by moving one or more lens elements in an optical axis direction.
2. Description of the Prior Art
Various imaging device modules configured to take digital images have been proposed. Such imaging device modules incorporate a lens system for optically forming an image of an object and an image pickup device such as a CCD image sensor for converting the object image formed through the lens system into an electrical signal. Additionally, in this type of imaging device module, specifically in the type of imaging device module having a zooming function for varying the focal length of a lens system and an AF (autofocus) function for bringing an object into focus automatically, one or more lens elements are moved in an optical axis direction; however, during this lens movement, a shutter unit also needs to be moved in the optical axis direction. Since the shutter unit is composed of a mechanical shutter which is opened and shut in accordance with electrical signals, the shutter unit is electrically connected to a circuit board via a flexible PWB (flexible printed wiring board) which is easily deformed in response to movements of the shutter unit.
For instance, although the lens barrel disclosed in Japanese unexamined patent publication 2004-334101 is related to retractable lens technology for a camera, this publication describes the same shutter unit technology as the above described shutter unit in that a shutter unit composed of a mechanical shutter is moved with a lens group in an optical axis direction, and adopts a structure using a flexible PWB which is connected to the shutter unit so that the wiring board which is connected to the shutter unit can follow movements of the shutter unit. Since a flexible PWB can be easily deformed in the direction of the thickness thereof, electrically connecting the shutter unit to a circuit board on a camera body via a flexible PWB makes it possible to maintain electrical connections between the shutter unit and the circuit board by flexible deformation of the flexible PWB even if shutter unit is moved in the optical axis direction.
In this type of lens barrel in which a shutter unit is electrically connected to a circuit board via a flexible PWB, the elastic deformation of the flexible PWB needs to be limited so that an elastically deformed portion of the flexible PWB does not enter an optical path of a lens system to intercept a light bundle of an object image when the flexible PWB is elastically deformed. To this end, in the above noted Japanese unexamined patent publication, the lens barrel is provided on one side thereof with a recessed portion in which such an elastically deformed portion can be accommodated. This elastically deformed portion is retracted into the recessed portion that is position off (away from) an optical path of the lens system to thereby prevent the elastically deformed portion from intercepting a light bundle of an object image when the flexible PWB is elastically deformed by a retracting movement of the lens barrel.
Since such a recessed portion is formed on an external wall of the lens barrel in the technique disclosed in the above noted Japanese unexamined patent publication, providing the recessed portion increases the outer diameter of the lens barrel, thus becoming an obstacle to miniaturization of the lens barrel. Specifically, there has been a demand for miniaturization of the imaging device module used for cameras produced in recent years such as digital cameras and cameras integrated into cellular phones, and accordingly, it is difficult to adopt the structure disclosed in the above noted Japanese unexamined patent publication that increases the outer diameter of the lens barrel. Additionally, since the flexible PWB is bent when elastically deformed in the lens barrel, the resistance to the flexible PWB increases at the elastically deformed portion and increases a load on movements of the shutter unit when moved in an optical axis direction, thus becoming an obstacle to miniaturization of a mechanism (including a drive motor) for moving the lens group and the shutter unit. Moreover, since the flexible PWB easily comes in contact with the inner wall of the lens barrel when elastically deformed, a frictional force produced at the contacting portion between the flexible PWB and the inner wall of the lens barrel further increases the load on movements of the shutter unit when moved in an optical axis direction.